Image-reading devices for reading images of sheets of original commonly use light sources to reflect light off the sheets. When reading a plurality of sheets of original fed sequentially with a gap formed between the trailing edge of each sheet and the leading edge of the next sheet, some conventional image-reading devices are configured to control the intensity of light emitted from the light sources during an inter-sheet period. The inter-sheet period is an interval in which the device is not reading a sheet of original that occurs between reading periods for reading successively fed the sheets. One conventional image-reading device continues to illuminate a light source during the inter-sheet period at the same intensity used during a reading period, while another conventional image-reading device extinguishes the light source during the inter-sheet period.